The present invention relates to porous sound-absorbing ceramic forms such as porous sound-absorbing bricks, tiles and other plate-shaped materials produced from perlite as a main raw material. The present invention also relates to a method of producing such porous sound-absorbing ceramic forms.
Sound-absorbing materials constituting soundproofing walls used for roads, buildings, etc. are demanded to absorb sound in the frequency range of 400 to 4000 Hz, which human beings are likely to feel to be a loud noise. It is particularly demanded to absorb sound in the frequency range of 800 to 2000 Hz.
Sound-absorbing materials containing mineral fiber such as glass wool or rock wool have heretofore been known as typical sound-absorbing materials. The mineral fiber-containing sound-absorbing materials suffer, however, from some disadvantages. That is, when the mineral fiber-containing sound-absorbing materials contain water, the sound-absorbing performance is markedly degraded. In addition, because they are made of fibers, the mineral fiber-containing sound-absorbing materials may become deformed with time and are likely to be scattered or peeled off by a high-speed air stream. Further, the resin material contained as a binder may be deteriorated by ultraviolet rays.
To overcome the disadvantages, the conventional practice is to cover the mineral fiber-containing sound-absorbing materials with resin films and to accommodate them in metallic containers. However, this causes the cost to increase considerably.
A sound-absorbing material consisting of gypsum board provided with a large number of through-holes is also well known. However, the sound-absorbing material consisting of perforated gypsum board has the following problem. The gypsum board does not have sound-absorbing performance but absorbs sound energy by resonance in the through-holes. Therefore, the sound-absorbing material can absorb sound only at specific frequencies. To solve this problem, the conventional practice is to provide an air layer at the back of the gypsum board or to install a backing material, e.g. glass wool, on the back of the gypsum board. These methods, however, require a great deal of time and labor for construction.
Meanwhile, ceramic tiles and bricks made by firing silicate minerals have heretofore been used as building materials, furnace materials and so forth. Moreover, various ceramic materials are being used for noise control measures in urban and industrial environments.
However, low-cost ceramic materials having excellent sound-absorbing qualities have not yet been provided, and hence no reduction in the cost of construction has yet been attained.
In view of the above-described conventional circumstances, the present invention provides low-cost porous sound-absorbing ceramic forms, such as sound-absorbing bricks and tiles, which have good weatherability and exhibit excellent sound-absorbing characteristics over a wide frequency range from low frequencies to high frequencies which human beings feel to be a loud noise.
That is, the present invention provides porous sound-absorbing ceramic forms and methods of producing the same, which have the following structures and arrangements.
(1) A porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.3 to 1.5, wherein the porous ceramic material consists essentially of 100 parts by weight of perlite having a particle diameter of 0.10 to 8.0 mm, 80 to 250 parts by weight of at least one sintered material selected from the group consisting of fly ash, slag, silica, volcanic ejecta, rock, and clay mineral as a matrix material, and 5 to 30 parts by weight of an inorganic binder, which have been sintered so that the matrix material, together with the binder, surrounds the perlite particles, and wherein the perlite particles form communicating openings at mutually contacting portions thereof, so that the internal pores are communicating pores.
(2) A porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.5 to 1.0, wherein the porous ceramic material consists essentially of 100 parts by weight of perlite having a particle diameter of 0.50 to 2.0 mm, 100 to 200 parts by weight of at least one sintered material selected from the group consisting of fly ash, chamotte, wollastonite, slag, silica, volcanic ejecta, rock, and clay mineral as a matrix material, and 10 to 20 parts by weight of an inorganic binder, which have been sintered so that the matrix material, together with the binder, surrounds the perlite particles, and wherein the perlite particles form communicating openings at mutually contacting portions thereof, so that the internal pores are communicating pores.
(3) A porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.5 to 1.0, a bending strength of 10 to 28 kgf/cm2 and a compressive strength of 40 to 90 kgf/cm2, wherein the porous ceramic material consists essentially of 100 parts by weight of perlite having a particle diameter of 0.50 to 2.0 mm, 100 to 200 parts by weight of sintered fly ash as a matrix material, and 10 to 20 parts by weight of an inorganic binder, which have been sintered so that the matrix material, together with the binder, surrounds the perlite particles, and wherein the perlite particles form communicating openings at mutually contacting portions thereof, so that the internal pores are communicating pores.
(4) A porous sound-absorbing ceramic form as stated in any one of the above paragraphs (1) to (3), wherein the perlite is one obtained by fire-expanding ground pearlite, obsidian or pitchstone.
(5) A porous sound-absorbing ceramic form as stated in any one of the above paragraphs (1) to (4), wherein the matrix material contains 10 to 50 parts by weight of glass.
(6) A porous sound-absorbing ceramic form as stated in any one of the above paragraphs (1) to (5), wherein the perlite and/or the matrix material has been crystallized by addition of a nucleation agent for crystallization.
(7) A porous sound-absorbing ceramic form as stated in any one of the above paragraphs (1) to (6), wherein the matrix material further contains 1 to 10 parts by weight of at least one short fiber material selected from the group consisting of metallic fiber, glass fiber, carbon fiber, ceramic fiber, mineral fiber, and whisker.
(8) A porous sound-absorbing ceramic form as stated in any one of the above paragraphs (1) to (7), which is brick.
(9) A porous sound-absorbing ceramic form as stated in any one of the above paragraphs (1) to (7), which is tile of other plate-shaped material.
(10) A method of producing a porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.3 to 1.2, the method including the steps of: mixing together 100 parts by weight of perlite having a particle diameter of 0.10 to 3.5 mm, 100 to 250 parts by weight of at least one powder selected from the group consisting of fly ash, chamotte, wollastonite, slag, silica, volcanic ejecta, rock, sludge, and clay mineral, 5 to 30 parts by weight of a binder, and 10 to 50 parts by weight of water; forming the resulting mixture into a predetermined shape, followed by drying; and firing the mixture at 900 to 1200xc2x0 C.
(11) A method of producing a porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.5 to 1.2, the method including the steps of: mixing together 100 parts by weight of perlite having a particle diameter of 0.50 to 2.0 mm, 35 to 60 parts by weight of at least one powder selected from the group consisting of fly ash, chamotte, wollastonite, slag, silica, volcanic ejecta, rock, sludge, and clay mineral, 10 to 25 parts by weight of a binder, and 20 to 45 parts by weight of water; pressing the resulting mixture in a frame mold with a predetermined shape under a pressure of 8 to 15 kgf/cm2, followed by drying; and firing the mixture at 950 to 1150xc2x0 C.
(12) A method of producing a porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.5 to 1.0, a bending strength of 15 to 28 kgf/cm2 and a compressive strength of 40 to 90 kgf/cm2, the method including the steps of: mixing together 100 parts by weight of perlite having a particle diameter of 0.50 to 2.0 mm, 35 to 60 parts by weight of fly ash, 10 to 25 parts by weight of a binder, and 20 to 45 parts by weight of water; pressing the resulting mixture in a frame mold under a pressure of 8 to 15 kgf/cm2, followed by drying; and firing the mixture at 950 to 1150xc2x0 C.
(13) A method of producing a porous sound-absorbing ceramic form as stated in any one of the above paragraphs (10) to (12), wherein the binder is water glass.
(14) A method of producing a porous sound-absorbing ceramic form as stated in any one of the above paragraphs (10) to (13), wherein a nucleation agent for crystallization of glass is added to the mixture.
(15) A method of producing a porous sound-absorbing ceramic form as stated in the above paragraph (14), wherein an annealing treatment for promoting the crystallization of glass is performed after the firing of the body.
(16) A method of producing a porous sound-absorbing ceramic form as stated in any one of the above paragraphs (10) to (15), wherein the binder contains an organic binder.
(17) A method of producing a porous sound-absorbing ceramic form as stated in any one of the above paragraphs (10) to (16), wherein the body is formed by further adding 5 to 10 parts by weight of at least one selected from the group consisting of metallic fiber, glass fiber, carbon fiber, ceramic fiber, mineral fiber, organic fiber and whisker to 100 parts by weight of fly ash powder having a particle diameter of 5 to 50 xcexcm.
(18) A method of producing a porous sound-absorbing ceramic form as stated in any one of the above paragraphs (10) to (17), wherein the porous sound-absorbing ceramic form is brick.
(19) A method of producing a porous sound-absorbing ceramic form as stated in any one of the above paragraphs (10) to (17), wherein the porous sound-absorbing ceramic form is tile of other plate-shaped material.